It is known that hair loss occurs after chemotherapy, hematopoietic stem cell transplantation, and radiation, but the underlying mechanism, clinical and histopathological characteristics, and standard treatment among them remain unclear. We retrospectively investigated 17 Japanese patients with hematologic disorders who had hair loss after hematopoietic stem cell transplantation and chemotherapy with or without radiation therapy. Details of the treatment, trichoscopic, and histopathological findings were evaluated, and the therapeutic effects were assessed quantitatively. Diffuse hair loss was observed in all patients, with an average duration of 4.9 years. Cyclophosphamide was the most frequently used chemotherapeutic agent, while peripheral blood stem cell transplantation was the most common transplantation method. Trichoscopy showed short vellus hairs and hair diameter diversity. Histopathologically, the proportion of vellus hair and that of catagen/telogen hair increased. Treatment primarily targeting hair follicle miniaturization improved hair volume in 52.9% of cases. Main pathology is considered the hair miniaturization rather than inflammation-mediated change in the chronic phase of hair loss. Therapies targeting follicular miniaturization, exemplified by topical minoxidil, have the potential to induce hair regrowth.
Seshimo et al. (Mon,) studied this question.